Reversing gear mechanism



plrrill W9 l.. W H. MARR REVERSING GEAR MEGHANISM Filed Aug. 2, 1952 3 Sheets-SMHl l INVENTOR will 9 ln W. H. MARR REVERSING GEAR MECHANISM Filed Aug. 2, 1932 3 sheets-sheet 2 Cil Patented Apr. 7, 1936 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to reversing gear mechanism for steam engines, and more particularly to improvements in the mechanism for operating the reversing gear.

One object of this invention is to provide mechanism for operating the reversing gear on a` steam engine which will eliminate the old formof hand operating lever and consequently, the physical effort ordinarily expended in moving said lever back and forth.

Another object is to provide simple mechanism for operating the reversing gear on a steam engine in Which the crosshead, the crosshead guides, pitman rod and the like ordinarily used with such mechanism are eliminated.

A further object is to provide a dual cylinder l mechanism for operating the reversing gear of a steam engine.

A still further object is to provide a dual cylinder for operating the reversing gear on a steam engine, one cylinder of Which is adapted to operate the device and the other to retard the stroke of the device and cushion the ends of said stroke whereby quiet and efficient operation of the device is obtained.

A still further object is to provide a dual cylinder mechanism for operating the reversing gear of a steam engine which is so mounted that one end thereof is free to oscillate and conform to the arc described by the reversing gear lever.

These and other objects of my invention which will be hereinafter made apparent toI those skilled in this particular art are accomplished by means of this invention, one embodiment of which is described in the following specification' and illustrated in the accompanying drawings, wherein:

Figure 1 is a View in elevation of the reversing gear for a steam engine and having my improved mechanism for operating the reversing gear shown in longitudinal section, a portion ofthe eccentric rods being broken away forv convenience of illustration Fig. 2 is a plan view of the mechanism illustrated in Figure l having portions thereof broken away;

Fig. 3 is a partial section View showing the steam cylinder of the mechanism and the steam passages thereto;

Fig. 4 is a view in section taken on lines Iii-IV of Figure 1;

Fig. 5 is a view on line V-V of Figure 1;

Fig. 6 is a view on line VI-V of Figure 1r;

Fig. 7 is a view in longitudinal vertical section of a modification of my device;

Fig. 8 is a partial plan View of the modification shown-in Fig; '7, and

Fig. 9 is a partial plan view of another modication of my device.

Referring to the drawingsin detail, I0 designates a valve rod on a steam engine one end of which is connected to the inlet valve (not shown) ofthe steam engine while the opposite end thereof is connected tofa link block I I. The link block II is slidably mounted in a slot I2 formed in a movable link I3 to the opposite ends of which the ends'of eccentric rods I4 and I5 are pivoted. The link' I3` has lugs I6 and I'I projecting therefrom to which the eccentric rods I4 and I5, respectively are pivoted.

The opposite ends of these eccentric rods I4 and I5 are connected tothe collars I8 and I9, re'- spectively, Which surround eccentrics 20 and ZI, mounted on a driven shaft 22 of the engine. These eccentrics 20 and 2I are 180 out of phase.

The above mechanism constitutes the reversing gear for a steam engine and to change the engine from forward to reverse or vice versa; the linkv I31is moved up or down so that the block II` is positioned in one end or the other of the slot I2. Assuming that the link I3 has been moved so that the link block I'I is at the bottom of the slot I2, then the valve rod I0 is directly opposite the eccentric rod I 5 and since it is being movedforward and backward due to the turning of the eccentric 2 I-it imparts a straight-line movement to the rod Iand operates the inlet valve of the engine. At the same time, the end of the eccentric rod I4 which is'being moved forward and backward by its eccentric 20, imparts an oscillating motion to the linkV I3v4 and causes it to swing about the sliding block- II as a pivot. To reverse the direction of the engine, the link I3 is moveddown until the block I I is in the upper end of the slot I2 and the eccentric rod I4 is in substantially the same straight line as the valve rod I0.

In order thatl this reversing gear may be readilyoperated to change the engine from forward to reverse, or vice versa, I have provided a simple mechanism for raising or lowering the link I3 relative to the link block I I.

My improved mechanism for operating this reversing mechanism comprises a member 2-3 having dual cylinders 24 and 25 formed therein, one above the other and opening at opposite ends of the member. Mounted in the cylinder 24 is a pistonZI` having a piston rod 21 connecting it with a head 28 which is pivoted toa lever 29 keyed to ashaft 3|).

From' the construction thus .fary it is apparent Cil that as the piston 2G is moved back and forth in the cylinder 24, the lever 29 is swung through an arc and turns the shaft 36. In order to raise and lower the link I3 as the piston 26 moves in and out of the cylinder, an arm 3| is provided one end of which is keyed to the shaft 30 and the other` end is pivoted to a lug 3| which in turn is pivoted to a lug 32 depending from the bottom of the link I3.

As the lever 29 is swung through an arc, it is apparent that the head 28 to which the piston rod 2l is rigidly connected will be oscillated back and forth and conform to the arc of the lever 29. To permit the outer end of the cylinder to travel in an arc, the open end of the cylinder 24 is closed by a head 33 having a trunnion 34 formed integral therewith which is mounted in a support secured to the engine in any suitable manner. The trunnion 34 is held in the support 35 by means of a cap 36 which is secured to the support by bolts 31.

To move the piston forwar-d in the cylinder 24, so as to turn the lever 29 and shaft 30, the cylinder head 33 and trunnion 34 have a passageway 38 (Fig. 3) therethrough to which a pipe 39 is connected by means of a swinging connection. The pipe 39 leads to a suitable source of motive power, such as steam, compressed air, or the like, the admission of which into the cylinder is controlled by a hand operated three-way valve 40.

When the valve 40 is turned in one direction motive power is delivered to the interior of the cylinder 24 through the pipe 39 and passageway 38 and forces the piston 26 to move toward the outer end of the cylinder. Since the outer end of the cylinder 24 is closed, it is necessary in order to secure the full stroke of the piston 26, that an opening 4l be formed through the side of the cylinder to permit the air in the forward end thereof to be readily exhausted.

To prevent the piston 26 from slapping against the. closed end of the cylinder 24 when it is being moved forward, I provide a cushioning means for retarding the forward speed of the piston. This cushioning means comprises a piston 42 mounted in the cylinder 25 and connected by means of a piston rod 43 to the head 28 so that the pistons in both of the cylinders 24 and 25 act simultaneously.

To cushion the forward movement of the piston 26, the forward end of the cylinder 25 is connected to a needle valve 44 through which the air in the cylinder 25 is exhausted. By regulating the needle valve 44 it is apparent that the amount of air being exhausted from the cylinder 25 may be controlled and consequently the speed of the piston 26 may be readily regulated. By retarding the exhaust through the needle valve 44, the air in the forward end of the cylinder 25 is compressed and effectively cushions the forward stroke of the pistons 26 and 42. The open end of the cylinder is closed by a cylinder head 45 having an opening therethrough for receiving the piston rod 43. Air is prevented from escaping around the piston rod by means of a packing 46 and packing gland 41.

To return the piston 26 to the opposite end of the cylinder 24 and reverse the direction of the engine, the valve 4U is turned so that the interior of the cylinder 24 is connected to an exhaust pipe 48 so that the force holding the piston 26 against the front end of the cylinder will be released. The pistons 26 and 42 are then moved to the rear ends of the cylinders 24 and 25, respectively, by the force of gravity working on a weight 59 (Fig. 2) mounted on a lever 5| keyed to the shaft 30.

This weight turns the shaft 30 and through the lever 29 and head 28 the pistons are forced rearwardly in the cylinders.

In order to retard the return movement of the piston 26 and to prevent slapping, the rear end of the cylinder 25 has an opening formed therein which leads to a needle valve 52. By adjusting the opening in the needle valve, it is apparent that sunicient air may be retained within the cylinder 25 to cushion the movement of the pistons and retard the movement of the piston 26.

To secure the correct valve setting of the inlet valves of the engine whether the engine is running forward or backward, I provide stops 53--54 for limiting the turning movement of the shaft 30 in each direction. These stops 53 and 54 are secured to the lever 29 and are so arranged that when the lever is moved in one direction, the stop 53 comes in contact with an adjusting screw 55 and when turned in the opposite direction, the stop 54 comes in contact with an adjusting screw 56. These adjusting screws 55 and 56 make it relatively easy to maintain the stops in the proper position to maintain the valves in their proper set positions.

In Fig. '7, I have shown a modification of my device in which the piston 26 not only operates the device, but also forms its own cushion during the forward stroke thereof while the piston 42 merely acts to cushion the rearward or return stroke of the pistons.

In this modification the opening 4I formed in the cylinder 24 instead of communicating with the atmosphere, has a needle valve 66 connected thereto which regulates the compressed air pressure in the forward end of the cylinder and also the speed at which the air is exhausted therefrom. By properly setting the valve 60, the forward stroke of the piston 26 will be cushioned and slapping will be prevented.

So that the piston 42 will not have any effect in retardng the forward stroke of the piston 26, the cylinder head 45 closing the end of the cylinder 25 has a vent 62 therein which permits the air in the forward end of the cylinder to be readily exhausted. The vent 62 connects the interior of the cylinder on the forward side of the piston 42 with the atmosphere and as a result, the piston offers no resistance to the forward movement of the piston 26. To cushion the return movement of the device, the rear end of the cylinder 25 has a needle valve 63 connected thereto which regulates the discharge of air from the rear end of the cylinder and as previously described, controls the return speed of the piston 26.

When my improved mechanism for operating the reversing gear is to be used on a locomotive or the like type of steam engine, I prefer to use steam, compressed air, or other suitable motive fluid to positively drive the pistons back and forth in the cylinders, instead of a weight and lever to move them in one direction as heretofore described. With such engines, the front end of the cylinder 25 is connected to a suitable source of motive power which is admitted to the cylinder when it is desired to move the pistons 26 and 42 to the rear end of the cylinder.

As shown in Fig. 9, the valve 44 on the front end of the cylinder 25 is removed and a pipe 'l0 is connected thereto which leads to a suitable source of motive power. In order that the front end of the member 23 may be free to oscillate,

a swinging connection similar to the connection between the pipe 39 and trunnion 34, is provided between the pipe and the cylinder. Motive power for moving the piston rearwardly in the cylinder is introduced through pipe 10 leading from a suitable source of supply and connected to pipe 'I0 by a three-way valve 1|, the other outlet of which is connected to an exhaust 12. To control the operation of the valves 40 and 1|, the valve 1| may be connected in any suitable manner such as lever 13, to the valve 40 in the line 39 so that when one valve is opened, the other will be connected to the exhaust and permit the pistons to be moved back and forth in the cylinders 24 and 25. When both of the pistons 26 and 42 are positively driven, the end of each of the cylinders opposite from where the motive power is admitted has a needle valve connected thereto for controlling the discharge of air from the cylinders and cushion the ends of the stroke of the pistons as previously described.

From the foregoing description it is readily apparent that I have provided mechanism for operating the reversing gear of a steam engine which is simple in construction, has few parts, and is positive in operation. My improved device is adapted to be connected directly to the lever of the reversing gear and by having the device mounted to permit oscillation the need of the crosshead, crosshead guides and pitman rods commonly employed in the mechanisms now used for operating the reversing gear are thereby eliminated.

What I claim as new and desire to secure by Letters Patent is:

The combination with the lever of the reversing gear for a steam engine, of mechanism for moving said lever back and forth comprising a block having bores extending thereinto from opposite sides thereof forming parallel, oppositely opening cylinders therein, one of which forms a Working cylinder and the other of which forms a cushioning cylinder, a cylinder head for the open end of each of said cylinders, a ported trunnion on the cylinder head closing said working cylinder, means for securing said trunnion to said engine whereby the opposite end of said block is movable through an arc, a piston in each of said cylinders, a head pivotally mounted on said lever, a piston rod connecting the piston in each cylinder with the head on said lever, means for admitting motive fluid through said ported trunnion to one of said cylinders to move the pistons and head in one direction and turn said lever, and mechanical means associated with the lever for returning the pistons to the opposite end of the cylinders.

WILLIAM H. MARR. 

